Conventionally, the grommet disclosed in Patent Document 1 has been known as this type of grommet. In the grommet disclosed in Patent Document 1, a large-diameter tubular portion is provided on the outer circumferential surface with a plurality of projecting portions that extend in the axial direction and are spaced apart from each other in the circumferential direction. Each of the projecting portions includes a diameter-enlarging slant portion that extends from a side of a small-diameter tubular portion through a contact point that comes into contact with an inner circumferential surface around a through hole upon inserting the grommet into the through hole to a bending point, the slant portion being slanted in parallel to the outer circumferential surface of the large-diameter tubular portion, and a diameter-reducing slant portion that extends from the bending point to a front end on a vehicle body locking recess side and inclines in the reversed slant direction.